Mediation system for a telephone network

ABSTRACT

A mediation system for a telephone network. The telephone network includes a plurality of signaling service points (SSPs) communicating message signaling unit (MSU) data with a plurality of signal transfer points (STPs). The MSU data is routed on data links connecting the plurality of SSPs and STPs. The mediation system includes a probe and a mediator. The probe is connected to at least one of the data links for intercepting the MSU data routed on the one data link, and the mediator is coupled to the probe for collecting the MSU data generating a call detail record (CDR). The probe intercepts either A-link data and/or E-link data on the data links. The mediator correlates the MSU data against a call list and generates either a full CDR or a partial CDR depending on a mode selected by a user of the system.

TECHNICAL FIELD

The present invention relates, in general, to telephone networks and,more specifically, to a system that passively monitors telephoneservices and traffic in a telephone network and reports the same to auser.

BACKGROUND OF THE INVENTION

Modem telephone networks require a signaling system for management of avariety of call setup and control functions, such as call routing andbilling. One version of a signaling system is a Common Channel SignalingSystem No. 7, referred to as SS7. The SS7 follows an internationalstandard defined by the International Telecommunications Union (ITU),and its variants such as those defined by the American NationalStandards Institute (ANSI) and Bell Communications Research (Bellcore).

The telephone network typically includes a plurality of offices throughwhich telephone calls may be routed, each office being owned by atelephone company that participates in the network. The telephonecompany may be a Regional Bell Operating Company (RBOC) of anIndependent Telephone Company (ITC), for example. Each office includes asignaling service point (SSP) for formulating a message signaling unit(MSU). An MSU may include a request for data pertinent to a particularcall or a message for setting up a call. In the terminology used in theSS7 system, these offices are referred to as having SP (signaling point)capability.

Within each RBOC or ITC, the SS7 includes one or more signal transferpoints (STPs). Each STP is essentially a specialized packet switch forreceiving and transmitting digital data using packet switch technology.Each office with a SSP is coupled to an STP. Typically, several SSPs maybe coupled to a single STP. In addition, communications betweendifferent telephone companies may be between their respective STPs.

In an SS7 system, an SSP may be coupled to an STP by way of a digitallink, referred to as an A-link. Furthermore, an STP may be coupled toanother STP by way of a different digital link, referred to as a B-link.A B-link typically includes a data transfer rate of 56 kbps.

A conventional telephone network, designated 10, is shown in FIG. 1. Asshown, ITC 12 and ITC 14, respectively including SSP 24 and SSP 26 arecoupled via A-links to a hub-STP 20. RBOC 16 and RBOC 18, respectivelyincluding STP 28 and STP 30 are coupled to hub-STP 20 via B-links. Inthe network shown, STP 20 is referred to as a hub-STP, because of itscentral position in the network architecture. The primary function ofhub-STP 20 is to route SS7 messages from one SSP to another, forexample, between SSP 24 and SSP 26 or between STP 28 and STP 30.

These messages, termed MSUs, include queries, responses to queries, andtrunk signaling messages. By way of example, an MSU may be a messagerequesting information as to whether a credit card number was valid. Aresponse may be the requested validation information. A trunk signalingmessage may be a message to set up a voice circuit in the existingnetwork. Each time that an MSU is received by hub-STP 20, a copy of theMSU is also received by billing system 22. The received MSU data isprocessed by the billing system to produce invoices, bills and reports,as further described in U.S. Pat. No. 5,008,929 issued Apr. 16, 1991 toOlsen et al.

Additional description of the SS7 system and various MSU types isprovided in U.S. Pat. No. 5,008,929, which is incorporated herein byreference.

In the network shown in FIG. 1, billing system 22 monitors MSU messagesreceived from hub-STP 20. Billing system 22 depends on hub-STP 20 toreformat the MSU messages from the other SSPs and STPs and then transmitthe messages to the billing system. Reconstructing the messages as theyappear across multiple links in a typical SS7 distributed network islaborious and time consuming.

Billing system 22 processes the MSUs to produce usage data thatindicates service recipients and service providers. The servicerecipient is the telephone company that own the SSP that formulated theMSU, and the service provider is the telephone company that provided thecall data for the MSU, or that transported the MSU. The usage data maythen be used to produce invoice data for assigning costs among thetelephone companies. Independent verification of the accuracy of theusage data and assigned costs by a telephone company is also laboriousand time consuming.

The deficiency of the conventional system to consolidate and correlatedata across multiple links of a typical distributed SS7 network showthat a need still exists for an improved system. In addition, a needexists for an independent system to verify the reliability and accuracyof usage data provided by a conventional system, such as billing system22.

SUMMARY OF THE INVENTION

To meet this and other needs, and in view of its purposes, the presentinvention provides a mediation system for a telephone network. Oneembodiment, includes a telephone network having a plurality of signalingservice points (SSPs) communicating message signaling unit (MSU) datawith a plurality of signal transfer points (STPs). The MSU data isrouted on data links connecting the plurality of SSPs and STPs. Themediation system includes a probe and a mediator. The probe is connectedto at least one of the data links for intercepting the MSU data routedon the one data link, and the mediator is coupled to the probe forcollecting the MSU data and generating a call detail record (CDR). Inanother embodiment, the probe is connected to a plurality of data links,wherein the plurality of data links route MSU data to one of the STPs.The probe intercepts either A-link data and/or E-link data on the datalinks. The probe includes a filter for filtering MSU data. In anotherembodiment, the mediator includes a correlator for sorting the MSU datainto queues, each of the queues store MSU data from a single data link.The correlator includes a data router for routing MSU data from a datalink to a predetermined queue.

It is understood that the foregoing general description and thefollowing detailed description are exemplary, but are not restrictive,of the invention.

BRIEF DESCRIPTION OF THE DRAWING

The invention is best understood from the following detailed descriptionwhen read in connection with the accompanying drawing. Included in thedrawing are the following figures:

FIG. 1 is a schematic diagram of a conventional telephone networking;

FIG. 2 is a schematic diagram of a mediation system of the presentinvention coupled to a telephone network; and

FIG. 3 is a schematic diagram of a mediator coupled to a probe inaccordance with the present invention.

FIG. 4 is a flow chart showing correlation processing steps in themediator in accordance with the present invention.

FIG. 5 is a state diagram depicting the generation of a full CDR in themediator in accordance with the present invention.

FIG. 6 is a state diagram depicting the generation of several partialCDRs in the mediator in accordance with the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIG. 2 the invention will now be described. A plurality ofSSPs, generally designated as 41-44, and STP 61 and STP 62 areinterconnected, as shown in telephone network 40. The SSPs communicatewith the STPs over A-links 45-52. STP 61 communicates with STP 62 overanother link 72. It will be appreciated that the SSPs and the STPs mayeach be located in a different region or locality.

In a typical arrangement, each SSP may be paired with two STPs. Forexample, SSP-1 is shown paired with STP 61 and STP 62. Pairing with STPsprovides redundancy and achieves better load balancing of call traffic.Although FIG. 2 shows that each SSP communicates with an STP over anA-link, it will be appreciated that an SSP may also communicate with anSTP over a different type of link, generally known as an E-link.Furthermore, each link, for example links 45-52, may be a set of linksfor redundancy and load balancing purposes. Thus, A-link 45 may be a setof 16 individual A-links coupled to STP 61. Although not shown, STP 61and STP 62 may each be a combined node, which provides both functions ofan SSP and an STP. SSP's 41-44 may also be combined nodes.

Also shown is probe 63 coupled to each A-link connected to STP 61. Asfour A-links are shown connected to STP 61, probe 63 may be connected byway of links 53-56 to respective A-links 45, 47, 49 and 51. Similarly,probe 64 may be coupled to each A-link connected to STP 62. Accordingly,probe 64 may be connected by way of links 57-60 to respective A-links52, 50, 48 and 46. It will be appreciated that probe 63 may bephysically located near STP 61 and probe 64 may be near STP 62. As willbe explained in greater detail below, each probe collects MSUs carryingcall information on each A-link coupled to an STP, or each E-linkcoupled to an STP.

Still referring to FIG. 2, mediator 65 is coupled to probes 63 and 64,while mediator 66 is also coupled to probes 63 and 64. Each mediatorcollects the MSUs from the probes, correlates the MSUs into calls andgenerates call detail records (CDRs). The CDRs may be sent to hostprocessor 67. Host processor 67 may further process the CDRs usingbilling verification and fraud detection algorithms. The processed datamay be stored in memory, displayed on monitor 70, or formatted into areport by printer 69.

Each mediator instructs a probe to collect MSUs from specific SS7 links.For example, mediator 65 may instruct probe 63 to collect MSUs on A-link45 and A-link 47 and instruct probe 64 to collect MSUs on A-link 46 and48. The probes then collect the MSUs. The MSUs received by the probe arein SS7 format, i.e., the data is binary and in a variable length format.The MSUs include IAM (initial address), SAM (subsequent address), ACM(address complete), ANM (answer), SUS (suspend), RES (resume), REL(release), RLC (release complete), CON (connect) and RSC (resetcircuit). Each link on the probe may be configured to have an address ofa mediator that indicates where to send the messages. The probe may sendthe messages directly to the mediator associated with the configured ismediator address (the destination).

In the preferred embodiment each probe may also filter the MSUs and sendfiltered data to the mediator. The format of raw SS7 messages on the SS7links and techniques for extracting data therefrom are well known tothose skilled in the art. A general description of the SS7 messages maybe found in U.S. Pat. No. 5,008,929 and is incorporated herein for itsteachings.

The probe may, for example, extract (or filter) destination andorigination point codes from the SS7 messages. The probe may alsoextract (or filter) all MSU data required for pricing and billinginformation.

The filtered messages are transmitted by the probe and received by themediator. As the mediator may receive messages from a plurality ofprobes, the messages are correlated by call, so that all SS7 messagespertaining to a call may be identified. Once identified and collected,the mediator may generate a complete call detail record (CDR) for thecall.

In the preferred embodiment, all SS7 messages from/to an SSP aredirected to the same mediator. If the SS7 messages from/to an SSP arenot directed to the same mediator, but are received by multiplemediators, there is a possibility that some messages may not becorrelated, or may need to be correlated at a higher level with someloss of scalability.

All messages of calls originating from and terminating at a particularSSP may be sent directly to a single mediator by monitoring all A-linksconnected to that SSP. For example, mediator 65 may be set up to receiveall A-link messages from SSP 41 by way of probes 63 and 64. By sendingall messages for a call to one mediator, the mediator has a highprobability of correlating the messages. In one embodiment of theinvention, messages that are not correlated are sent to the hostprocessor for correlation. In another embodiment, messages notcorrelated may be discarded.

It will be appreciated that the signaling link code (SLC) between twosignaling points, for example SSP 41 and STP 61, is a 4-bit code. The4-bit code allows for a maximum of 16 links in a link set. In theexemplary embodiment shown in FIG. 2, STP 61 and STP 62 may beconsidered a mated STP pair. Accordingly, any SSP may have up to 32links with any mated STP pair. For example, SSP 41 may have up to 16links to STP 61 and another 16 links to STP 62.

Each mediator normalizes the data received from the probes into partialor full CDRs. Messages of different protocols are normalized into acommon record format. The normalized record is then correlated into fullCDRs or partial CDRs containing the information for a call. There is aone-to-one relationship between the SS7 messages and the normalizedrecords.

Referring next to FIG. 3, one embodiment of a mediator, generallydesignated as 80, will now be described. As shown, a plurality of I/Omodules 90-92 are coupled to respective data links 87-89. I/O modules90-92 may be, for example, conventional Ethernet (10/100 Base TEthernet) connections using a protocol such as TCP/IP that allows highspeed communications with probes 81-83. Another TCP/IP connection mayalso be formed by way of I/O module 95 between a host processor andcontroller 94, as shown.

In operation, controller 94 waits for a connection request from the hostprocessor (for example processor 67) using TCP/IP protocol. Whenconnected, host processor 67 sends configuration commands to controller94 specifying which probes are to collect SS7 messages over specificlinks. Controller 94 then makes the TCP/IP connections to the probes.For example, FIG. 3 shows mediator 80 connected to probes 81-83.Controller 94 reformats the configuration commands from host processor67 into compatible probe commands. The probe commands specify the SS7messages desired to be collected from specific links. For example, probe81 may be commanded to collect and filter MSUs carrying call informationfrom a single or a plurality of links 84. Similarly, probes 82 and 83may be commanded to collect and filter MSUs from a plurality of links 85and a plurality of links 86, respectively.

The controller, by way of a software module, creates correlation groups,designated generally as 97, 98 and 99. Each correlation group includesseveral link frame queues to hold SS7 frames. One link frame queue holdsframes from a single SS7 link. For example, correlation group 1 holds anI-number of link frame queues, which may be frames from the set of Ilinks 84 obtained by probe 81. In another example, correlation group 2may hold a J-number of link frame queues from the set of J links 84 and85 obtained by probes 81 and 82. In yet another example, correlationgroup N may hold a K-number of link frame queues from the set of K links84, 85 and 86 obtained by probes 81, 82 and 83.

Link data router 93 routes link frames to their correct link framequeue. When a call completes, or times out, a correlation group, forexample correlation group 97, generates a CDR for the call and sends theCDR to host processor 67 by way of I/O module 95. As link data iscorrelated by the correlation group, the link data is checked for fieldsdenoting that a conversation, for example, is occurring. For example, tocorrelate ISUP messages into calls, point codes and trunk circuit IDfields may be used. The link data is also timestamped, an important partof completing a CDR.

It will be appreciated that different mediators may be configured tocollect and correlate link data from the same probe, but not from thesame link. This is illustrated, for example, in FIG. 2 which showsmediators 65 and 66 configured to collect and correlate data from probe63. In the preferred embodiment, however, mediator 65 may be configuredto collect data, for example, from A-link 45 and A-link 46, whereasmediator 66 may be configured to collect data from A-link 49 and A-link50. Since any probe link may be assigned to any mediator forcorrelation, the invention provides a mediation system that is flexibleand scalable.

The processing performed in each correlation group, for examplecorrelation group 1 (97) or correlation group 2 (98), will now bedescribed in greater detail by reference to FIG. 4. The correlatorprocessing steps are generally designated by 110, as shown. Thecorrelator waits for blocks of messages from the probes in step 112.When a block of SS7 messages is received, the block of messages arestored in step 113 in a link frame queue, for example, link frame queueA (shown in FIG. 3). It will be appreciated that each block of SS7messages is from a single link. Another block of messages from adifferent link, when received, is stored in another link frame queue. Acall list is also maintained in each correlation group, for example,call list 1 in correlation group 1 and call list 2 in correlation group2 (FIG. 3).

After a block of messages is received, decision block 114 is performed.If each link queue in the correlation group contains at least onemessage, then step 115 selects the next chronological message from allthe link queues. If one of the link queues is empty, processing in step112 waits for another block of messages. As each message has a timestamp (added by a probe that picked up the message), each receivedmessage is chronologically dated. The oldest message stored in the groupof link queues is selected for correlation in step 115. The correlatorattempts to find an associated or corresponding call object in the calllist to which the oldest message belongs (step 116). If the message isnot found in the call list (step 117), a check is made to determinewhether the message may be a new call. The check is performed in steps118, 119 and 121. Step 118 determines whether the message is an IAM(initial address message). If it is not, a single frame CDR is createdand sent with the data from the message (step 119). If the message is anIAM, however, a new call object is created in the call list. Thisprocess repeats, until one of the link queues is empty. Accordingly, thenext oldest message from the group of frame queues is selected (step115) and the search is made to determine whether this message is a newcall or is already in the call list. The repetition of this process isperformed by way of decision block 114.

If an associated call is found in the call list (step 117), the selectedmessage is used to transition the state of the call in step 120. Thetransition of states will be described in detail later. Whether a CDR isgenerated or not for a message event is determined by step 122. Thedecision for generating a CDR for a message event will also be describedlater. Generally, a full CDR or a partial CDR may be generated. A fullCDR is generated when the message event is, for example, a releasecomplete having occurred as a result of a RLC message having beenreceived in a link frame queue. Partial CDRs may also be generatedduring message events prior to a release complete event. For example, anaddress complete event, occurring as a result of an ACM message havingbeen received in the link frame queue, may generate a partial CDR.

If a CDR is to be generated, the data from a call object in the calllist is transferred to create a CDR object (step 123). The CDR is thensent to a host processor, for example. When all the messages that may bereceived for a call object in the call list have been processed, ordetermined by decision block 124, the call object is deleted from thecall list (step 125).

As discussed, when a block of messages is received (all the messagesbeing from one link), the messages are added to a link frame queue. Itwill be understood that the size of the block may be a variabledepending on the configuration of the probe. The block size depends onthe buffer size of the probe and may be, for example, 64 Kbytes. Theblock size may also depend on a settable timeout in the probe forreceiving messages, and may be set to 1 second, for example. Eachmessage in the block is also time stamped by the probe. As the messagesare time merged and correlated, it will also be appreciated that thecall list in each correlation group may be keyed on various fields inthe message. The call list may be keyed on, for example, originationpoint code (OPC), destination point code (DPC) and trunk ID (TCIC).

The generation of a CDR will now be described by reference to FIGS. 5and 6, depicting state diagram 130 and 150, respectively, for generatinga full CDR and a partial CDR. SS7 messages represent various eventsduring a call.

When an IAM (initial address) is received, new call state 131 in statediagram 130 (new call state 151 in state diagram 150) is entered. In onesequence of events, the address complete (ACM) message is received afterthe IAM message, thereby entering address complete state 132 in statediagram 130. Following the address complete state, answered state 133 isentered, because answer (ANM) is received. Next, release initiated state134 and release complete state 135 are sequentially entered in responseto REL (release) and RLC (release complete).

All transitions are either due to an SS7 message associated with a callor any of the following conditions: a timeout (TO), a sequence error(SE), reset circuit (RSC), suspend (SUS) and resume (RES). The statenames reflect the condition of the call. A sequence error is a messageassociated with a call that is received out of sequence. For example, itis expected that an ACM message would be received prior to an ANMmessage. After receiving an IAM, it is possible to receive an ACM, a RELor a SAM (subsequent address). If a SAM is received, SAM state 137 isentered, as shown. Any message from a specific state may only transitionto another state, as shown in FIGS. 5 and 6, otherwise a sequence erroris considered to have occurred. Although not shown in these figures, theCON (connect) message may substitute for both, the ACM message and theANM message. The CON message causes a transition to the answered state133.

A call which uses the full CDR state machine of FIG. 5 generates a fullCDR, as shown, after entering the release complete state 135. A callwhich uses the partial CDR state machine of FIG. 6 generates severalCDRs, as desired by the user. As shown in FIG. 6, a setup partial CDR isgenerated after entering address complete state 152. A single frame CDRis generated after entering answered state 153, and a teardown partialCDR is generated after entering release complete state 155.

The fields of the various CDRs are detailed in the following tables.Table 1 lists the fields in a full CDR. Table 2 lists the fields in asetup partial CDR. Table 3 lists the fields in a teardown partial CDRand Table 4 lists the fields in a single frame CDR. Table 5 lists thevariable parameter types that may be included in each of the CDRs. Theserial number field (one number) allows the host processor to correlatepartial CDR's. This may also be done with OPC/DPC/TCIC.

TABLE 1a Full CDR Field No. of Octets Description Serial Number 4Correlation Group Id 1 Protocol ID 1 Network Indicator 1 National orInternational, 14 or 24 Bit Data Length 2 Fixed Data Variable Depends onProtocol ID Field Optional Data Variable See Variable Parameter Types inTable 5

TABLE 1b Fixed Data for Full CDR Field No. of Octets Description OPC 4DPC 4 Trunk Id 2 Called Party Number 28  Calling Party Number 28 Calling Party Category 1 Carrier Identification 4 Release CauseIndicator 2 Reason 1 No Error (0) Timeout (1) Sequence Error (2) ResetCircuit (3) IAM Timestamp 8 Monitor Id for IAM 2 Link Number for IAM 1ACM Timestamp 8 Monitor Id for ACM 2 Link Number for ACM 1 ANM Timestamp8 Monitor Id for ANM 2 Link Number for ANM 1 REL Timestamp 8 Monitor Idfor REL 2 Link Number for REL 1 RLC Timestamp 8 Monitor Id for RLC 2Link Number for RLC 1

TABLE 2a Setup Partial (CDR) Field No. of Octets Description SerialNumber 4 Correlation Group Id 1 Protocol ID 1 Network Indicator 1National or International, 14 or 24 Bit Data Length 2 Fixed DataVariable Depends on Protocol ID Field Optional Data Variable SeeVariable Parameter Types in Table 5

TABLE 2b Fixed Data for Setup Partial CDR Field No. of OctetsDescription OPC 4 DPC 4 Trunk Id 2 Reason 1 No Error (0) Timeout (1)Sequence Error (2) Reset Circuit (3) Called Party Number 28  CallingParty Number 28  Calling Party Category 1 Carrier Identification 4 IAMTimestamp 8 Monitor Id for IAM 2 Link Number for IAM 1 ACM Timestamp 8Monitor Id for ACM 2 Link Number for ACM 1

TABLE 3a Teardown Partial CDR Field No. of Octets Description SerialNumber 4 Correlation Group Id 1 Protocol ID 1 Network Indicator 1National or International, 14 or 24 Bit Data Length 2 Fixed DataVariable Depends on Protocol ID Field Optional Data Variable SeeVariable Parameter Types in Table 5

TABLE 3b Fixed Data for Teardown Partial CDR Field No. of OctetsDescription Reason 1 No Error (0) Timeout (1) Sequence Error (2) ResetCircuit (3) Release Cause Indicator 2 OPC 4 DPC 4 Trunk Id 2 RELTimestamp 8 Monitor Id for REL 2 Link Number for REL 1 RLC Timestamp 8Monitor Id for RLC 2 Link Number for RLC 1

TABLE 4a Single Frame CDR Field No. of Octets Description Serial Number4 Correlation Group Id 1 Protocol ID 1 Network Indicator 1 National orInternational, 14 or 24 Bit Timestamp 8 Monitor ID 2 Link Number 1 DataLength 2 Fixed Data Variable Depends on Protocol ID Field Optional DataVariable See Variable Parameter Types in Table 5

TABLE 4b Fixed Data for Single Frame CDR Field No. of Octets DescriptionMessage Type 1 IAM = 1 SAM = 2 ACM = 5 ANM = 9 SUS = 13 RES = 14 REL =12 RLC = 16 RSC = 18 CON = 7 OPC 4 DPC 4 Trunk Id 2 Called Party Digits28  Release Cause Indicator 2

TABLE 5a Variable Parameter Types Name Encoding Event Event ParameterStructure (Timestamp; 8 octets) Charge Number Digit Parameter StructureGeneric Address (GAP) Digit Parameter Structure Generic Digits DigitParameter Structure Redirecting Number Digit Parameter StructureRedirection Number Digit Parameter Structure Original Called NumberDigit Parameter Structure Connected Number Digit Parameter StructureLocation Number Digit Parameter Structure Redirection InformationRedirection Information Structure (See Table 5b)

TABLE 5b Redirection Information Structure Redirection Type 1 octet Seebelow Redirection Reason 1 octet See below Redirection Count 1 octetNumber of redirection this call has undergone Original RedirectionReason 1 octet Same encoding as Redirection Reason. Not valid unlessRedirection count is 2 or more

TABLE 5c Redirection Type No Redirection 0 Call Rerouted 1 CallDiversion 2

TABLE 5d Redirection Reason Unknown 0 User Busy 1 No Reply 2Unconditional 3 Deflection 4 Mobile Subscriber not Reachable 5

What is claimed:
 1. In a telephone network having a plurality ofsignaling service points (SSPs) communicating message signaling unit(MSU) data with a plurality of signal transfer points (STPs), the MSUdata routed on data links connecting the plurality of SSPs and STPs, amediation system comprising: a probe connected to at least a first oneof the data links associated with a first one of the plural SSPs forintercepting first MSU data routed on the at least first one data link,and connected to at least a second one of the data links associated witha second one of the plural SSPs for intercepting second MSU data routedon the at least second one data link, and a first mediator coupled tothe probe for collecting the first MSU data and generating a first calldetail record (CDR); and a second mediator coupled to the probe forcollecting the second MSU data and generating a second CDR.
 2. In atelephone network having a plurality of signaling service points (SSPs)communicating message signaling unit (MSU) data with a plurality ofsignal transfer points (STPs), the MSU data routed on data linksconnecting the plurality of SSPs and STPs, a mediation method comprisingthe steps of: coupling a probe to a least a first one of the data linksbetween a first one of the plurality of SSPs and one of the plurality ofSTPs and to at least a second one of the data links between a second oneof the plurality of SSPs and one of the plurality of STPs; interceptingfirst MSU data routed on the at least first one of the data links andsecond MSU data routed on the at least second one of the data links;transmitting the first intercepted MSU data to a first mediation device;transmitting the second intercepted MSU data to a second mediationdevice; generating a first CDR from the first MSU data at the firstmediation device; and generating a second CDR from the second MSU dataat the second mediation device.